Lac-Mégantic: Sewage plant needs cleanup

Janet Bagnall, The Gazette01.10.2014

Jacques Dion of Sanexen, a contamination site remediation company, with equipement to treat oil contaminated sewage water at a temporary treament facility set up beside the water treament plant in Lac-Mégantic, Wednesday July 17, 2013, near site of the fatal train crash and explosion Saturday July 6th. Hundreds of thousands of litres of crude oil were spilled, much of it into the city’s sewage system. After the water is treated at the facility it is dumped into the local river.Phil Carpenter
/ Montreal Gazette

Water treatment technicians prepare a tank to treat oil contaminated sewage water at a temporary treatment facility set up beside the water treatment plant in Lac-Mégantic, Wednesday, July 17, 2013, near site of the fatal train crash and explosion Saturday July 6th. Hundreds of thousands of litres of crude oil were spilled, much of it into the city’s sewage system. After the water is treated at the facility it is dumped into the local river.Phil Carpenter
/ Montreal Gazette

A water treatment technician prepares a tank to treat oil contaminated sewage water at a temporary treatment facility set up beside the water treatment plant in Lac-Mégantic, Wednesday, July 17, 2013, near site of the fatal train crash and explosion Saturday July 6th. Hundreds of thousands of litres of crude oil were spilled, much of it into the city’s sewage system. After the water is treated at the facility it is dumped into the local river.Phil Carpenter
/ Montreal Gazette

Lac-Mégantic - Within minutes of the July 6 train derailment and explosion in downtown Lac-Mégantic, Marc Vallerand was racing toward the town's sewage treatment plant across the lake from the town centre turned firestorm.

Vallerand, the on-call operator at the filtration plant that weekend, arrived to find flames leaping from the water that poured through the sewage troughs at the plant. "What did I think? I didn't have time to think," said Vallerand. "We were running left and right trying to shut down the plant. By 4 a.m., we got it shut down."

But between the 1:20 a.m. explosion and the time the sewage plant stopped operating, the reservoirs had filled with oil-contaminated water.

Drinking water was never at risk from contamination, said Vallerand. Drinking water is handled by a different plant unconnected to the sewage system. The only danger to the drinking supply - it was a question of whether there would be enough of it to meet the needs of residents - came within the first 60 or so hours when firefighters were

forced to use clean water to fight the conflagration in Lac-Mégantic's centre. "As soon as they were able to draw water from the lake, the danger was over," said Vallerand.

The first three days after the explosion were harrowing, said Vallerand. "No one slept. Everyone was working flat out. I slept maybe two hours in the first 60 hours," he said.

The Usine d'épuration des eaux usées of Lac-Mégantic is tucked out of sight of passing traffic on land almost directly across the lake from what had been the town's lively downtown. Today, that downtown is recognizable by its charred, blackened centre and the bright yellow booms that were deployed across the waterfront to stop an estimated one million litres of crude oil trapped in tanker cars from spilling into the lake. Water pooled at the site July 6 became mixed with spilled oil, and found its way through sewage pipes to the filtration plant, Vallerand said.

The water treatment plant's two main reservoirs can treat thousands of cubic metres of sewage water at a time - which, after oil infiltrated, was how much had to be pumped out and stored

temporarily for treatment. The reservoirs first had to be cleaned of any trace of oil before treatment could get back underway, said Jacques Dion, vice-president of business development with Sanexen Services Environnementaux Inc. Brossard-based Sanexen is a private sub-contractor hired to clean the contaminated water pumped out of the devastated downtown site and transported to the treatment facility.

"So far, we have treated about 3,000 cubic metres (three million litres) of contaminated water," said Dion on Wednesday afternoon. The decontaminated and cleaned water is returned to the river, he said. "We test the water twice a day and the Ministry of the Environment comes two to three times a day to inspect the quality of the water."

A third and fourth reservoir at the treatment plant contained oil-contaminated water, waiting for treatment.

"The first two reservoirs are more than enough to meet the needs of the town," said Dion. "They don't use the third and fourth ones usually." They filled up July 6 in the hours before the plant was shut down.

Sanexen uses a three-step decontamination process: suspended solids are removed with filters; the water is then treated with an ultraabsorption system; lastly, it goes through a carbon filter.

The contaminated material that remains is transported to landfill sites designated for contaminates.

No one has any idea when the work of water decontamination will be finished, said Dion, even with workers on 12-hour SHIFTS AROUND THE CLOCK.

Ahead lies the ultimate challenge: soil decontamination, another area of expertise for Sanexen, whose work history includes decontaminating former U.S. military bases in the Arctic. At Lac-Mégantic, forensic experts with the Quebec coroner's office are still sifting through the soil of the worst of the devastation, which means a large part of the site remains off-limits to cleanup efforts.

Still on the site are a number of overturned tankers full of crude oil, remains of the 72-car train that derailed. They have to be pumped out and removed before decontamination work can start, town officials have said.

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